The present invention relates to an apparatus for starting and warming up an internal combustion engine adapted to suitably control the opening degree of a throttle valve during starting and warming up of the internal combustion engine.
Japanese Utility Model Publication No. 28856/1980 discloses an example of the apparatus for controlling the opening degree of a throttle valve during starting and warming up of an internal combustion engine. This apparatus has a heat-sensitive body adapted to change its volume in response to a change in the temperature of, for example, the engine cooling water, or in response to heat generated by an electric heat generating member. This heat-sensitive body engages with a fast idle cam which in turn engages with a throttle lever so as to bias the throttle valve in the closing direction. As the warming up of the engine proceeds to increase the temperature of the engine, the heat-sensitive body increases its volume to gradually decrease the opening degree of the throttle valve, thereby reducing the idle speed of the engine. In this known apparatus, the control cam contour of the fast idle cam for engaging with the throttle lever is as shown in FIG. 1. Namely, the cam contour A has an arcuate configuration, the radial distance of which from the shaft 7 rotatably carrying the cam is progressively decreased. This cam contour A is effective in controling the opening degree of the throttle valve during the warming up of the engine. Unfortunately, however, when the engine is left in the inoperative condition for a long period of time under normal atmospheric temperature conditions, the engine temperature is gradually raised to turn the fast idle cam 11 counter-clockwise as viewed in the drawings, by the expansion of the heat-sensitive body, so that the throttle lever 4 is rotated in the valve closing direction to reduce the opening degree of the throttle valve. In consequence, the engine speed is excessively lowered during the starting and warming up of the engine to take a lot of time till the completion of the warming up of the engine, thus causing not only an uneconomical use of the fuel but also an increase of noxious exhaust emission due to delay of the heating up of the exhaust gas cleaning system.